The resistance as a function of temperature (R–T) was measured using the in situ measurement with a heating rate of 10 °C min?1. The sample temperature was measured by a Pt-100 thermocouple located at a heating stage controlled by a TP 94 temperature controller (Linkam Scientific Instruments Ltd, Surrey, UK). The optical band gap was measured by NIR spectrophotometer. The phase structures of the films annealed at various temperatures were investigated by x-ray diffraction (XRD) analysis using Cu Ka radiation in the 2θ range from 20°to 60°, with a scanning step of 0.01°. The atomic force microscopy (AFM, FM-Nanoview 1000) was used to examine the surface topography.